1. Field of the Invention.
This invention relates to propellants for spinning rocket motors. More particularly, this invention relates to propellants which are loaded into rocket motors and ignited while the motors are spinning in flight.
2. Description of the Prior Art.
Rocket assisted projectiles (RAP's) are well known. A RAP is a projectile such as a warhead or artillery round which has a rocket motor attached to it to assist it in flight. A RAP is normally expelled from a gun with a rifled barrel which imparts both its initial forward impetus and a spinning motion to it. Then, after it is in flight, the attached rocket motor is ignited to give the projectile additional impetus. Since the projectile and the motor are spinning, motors attached to RAP's are called spinning rocket motors.
In the prior art, two types of motors have generally been utilized to assist RAP's. One type may be described as comprising a hollow cylinder closed at its forward end by a forward or front plate and partially closed at its rear end by a rigid base plate having an exhaust nozzle or port therethrough. The second type is well described in U.S. Pat. No. 3,434,419. It is similar to the first type with the exception that its base plate is slideably attached in a manner which permits the base plate to move forward in a piston-like manner when the motor is expelled from a gun. In order to be utilized as RAP motors, both types of motors have naturally been adapted, insofar as shape and external paraphernalia are concerned, to be expelled from guns. And, when such motors have been utilized as RAP motors, they have generally been charged with solid propellant grains.
The use of solid propellants creates many problems, especially with spinning rocket motors. Firstly, since the motor and the propellant contained therein both spin during flight there must be extremely strong bonding between the liner and the propellant grain. Extremely strong bonding is necessary to prevent the propellant grain from tearing free as a result of centrifugal force during flight. Secondly, since centrifugal force exerts tremendous pressures on the propellant grain, extreme care must be taken in loading and curing the propellant to insure that the grain does not become cracked or develop flaws. Further, after the propellant is loaded into the motor and cured, occasional inspections must be carried out to insure that a crack or flaw has not developed as a result of thermal cycles or mishandling.